I don't really have a lucky charm, and I'm not sure I believe in luck... but for the sake of the Saint Patrick's Day, I guess my favorite pen can be my lucky charm! (I always seem to pass tests with it...)
I've always had 13 as a lucky number. I've also always kept Lavender, Rosemary and Basil in my garden, for luck. And I do the usual things to ward of bad luck. Such as, crossing out black cats that come across my path and tossing spilled salt over my shoulder.